Miniature hearing aid insert modules are known.
In a German national patent application no. DE 43 35 941A1, there is described a hearing aid which is more concealed in use. The hearing aid includes a thin-walled, hard or flexible plastics material faceplate which is design to co-operate with the natural shell-like form of a human pinna. Moreover, the faceplate partially houses an electronic hearing aid amplification module which is also accommodated within an integral projection from the faceplate which is arranged to engage in use into an auditory canal associated with the pinna.
In an international PCT patent application no. PCT/DK02/00261 (publication no. WO 02/089524), there is described a hearing aid comprising a faceplate, a battery holder for accommodating a battery and a signal path incorporated within a shell part. The path includes a microphone coupled to a signal processor coupled in turn to an output acoustic transducer. The battery is connected via its battery holder to the signal processor for providing energization thereto when the aid is operational. The microphone and the battery holder with its associated battery are spatially disposed at the faceplate, whereas the signal processor and the output transducer are disposed in the shell part, the shell part being suitable for insertion into a human auditory canal in use. An insert module associated with the faceplate is used to house electrical connections from the aforesaid battery to the signal processor. Preferably, the insert module serves also to mechanically support the microphone.
U.S. Pat. No. 6,430,296 discloses a modular hearing aid comprising a hollow plug having a generally irregular conical shape and an exterior opening which is covered by a faceplate, in which a recess is formed for removable arrangement of a battery as well as an electronic module. The recess comprises a first region for insertion of the battery and a second region coherent with the first region for placing of a socket part of the electronic module. At the edge of the recess the faceplate is formed with engaging means for the socket part, whereas further parts of the electronic module are placed below the faceplate. The recess is formed such that at removal of the battery the first and second regions together allow passage also of further parts for removal of the complete electronic module from the modular hearing aid.
A disadvantage of the modular hearing aid disclosed in U.S. Pat. No. 6,430,296 is that resilient lugs 19 only contact the edge of the faceplate recess along a minor portion of the edge and leaves coupling between the hearing aid insert module and hearing aid faceplate fragile.
In case of computer aided manufacturing of individual shells for hearing aids technicians now laser scan the ear canal impression and all the resulting data of the shape of the ear is transferred into a specially developed computer modelling software program. Technicians can then design an on-screen 3D-computer model of the ideally shaped custom hearing aid, incorporating all the required miniature components in the available space. The data for this model is then transferred to the stereo lithography apparatus (SLA), which uses a laser to build-up the shell layer-by-layer within a bath of liquid photoplastic acrylic material. The custom shells made by this new process (SLA-shells) have a superior quality and consistency, resulting in smaller sized and better fitting hearing aids for the user. However, SLA-shells suffer from one significant drawback—namely that these shells are more fragile than traditional injection moulded shell parts of thermo-plastic material. Therefore, utilizing a substantially closed-loop frame in accordance with the present invention is a significant advantage since the closed-loop frame allows a large contact area between the insert module and hearing aid faceplate to facilitate a robust coupling.